Mobile x-ray apparatus are of particular value in intensive care unit (ICU) and other environments where timely acquisition of a radiographic image is important. Because it can be wheeled around the ICU or other area and brought directly to the patient's bedside, a mobile x-ray apparatus allows an attending physician or clinician to have recent information on the condition of a patient and helps to reduce the risks entailed in moving patients to stationary equipment in the radiological facility.
The perspective view of FIG. 1 shows an example of a conventional mobile x-ray apparatus that can be employed for computed radiography (CR) and/or digital radiography (DR). A mobile radiography unit 600 has a frame 620 that includes a display 610 for display of obtained images and related data and a control panel 612 with a keyboard that allows instruction entry for storing, transmitting, modifying, and printing of the obtained image.
For mobility, unit 600 has one or more wheels 615 and one or more handle grips 625, typically provided at waist-, arm-, or hand-level, that help to guide unit 600 to its intended location. A self-contained battery pack typically provides source power, eliminating the need for operation near a power outlet.
Mounted to frame 620 is a columnar support member 635 that supports an x-ray source 640, also termed an x-ray tube, tube head, or generator mounted on a boom apparatus 70, more simply termed a boom 70. In the embodiment shown, support member 635 has a vertical column 64 of fixed height. Boom 70 extends outward a variable distance from support member 635 and translates up and down column 64 to the desired height for obtaining the image. Boom 70 may extend outward by a fixed distance or may be extendible over a variable distance. Height settings for the x-ray source 640 can range from low height for imaging feet and lower extremities to shoulder height and above for imaging the upper body portions of patients in various positions. In other conventional embodiments, the support member for the x-ray source is not a fixed column, but is rather an articulated member that bends at a joint mechanism to allow movement of the x-ray source over a range of vertical and horizontal positions.
One concern that must be addressed in design of the support member relates to ease of positioning of the x-ray source mounted on its boom. For ease of operation under varying conditions, the technician should be able to easily position and orient the x-ray source without requiring both hands, without the need of additional tools, and without needing help from nearby personnel. This includes moving the x-ray source from its docked position used in transport to an imaging position. The mechanical problem of providing ease of positioning is complicated by the weight of the x-ray source and by its extension outward from the vertical axis,
While the conventional mobile x-ray apparatus described as unit 600 provides portable imaging capability in a number of applications, however, there are drawbacks to existing designs that can make these devices difficult to deploy in some circumstances. One of the problems common to conventional designs is due, in part, to the relative mobility and range of motion of the mobile x-ray apparatus that is needed.
The side view of FIG. 2 shows a significant problem that occurs when transporting a mobile radiography system, shown as a mobile radiography unit 62 that uses a fixed vertical structure, column 64. Boom 70 that provides transport of x-ray source 68, normally extended outward from unit 62 when in its imaging position, is folded back toward a technician 66 for transport. This transport position helps to protect the x-ray source from damage or from causing an obstruction during movement. Column 64, however, obstructs the view of technician 66 when moving the unit from one place to another, so that objects that are near the front edge of unit 62 or directly in front of the unit cannot readily be seen. The technician is required to peer around the column during transport and can be more prone to colliding or bumping against other equipment or obstacles in the hospital ward or other location. The fixed vertical column 64 may also present difficulties when passing or moving alongside accessory equipment, furniture, or patient support equipment. With obstructed vision, the technician must move slowly, impacting productivity and response time. Accidents and mishaps are more likely.
One type of solution for alleviating the visibility and mobility problems described with reference to FIG. 2 is to provide a collapsible column 64, as described in commonly assigned U.S. Patent Application Ser. No. 61/323,503 filed Apr. 13, 2010 in the names of Wendlandt et al. Making column 64 collapsible, such as using a telescopic column design, not only allows improved visibility during movement of the mobile radiography unit 62, but also provides a more favorable weight distribution that is more compact and has a lowered center of gravity, facilitating movement of the unit by the technician from room to room.
While the collapsible column has advantages over fixed column height, however, a number of problems remain to be solved. One area of particular interest relates to boom movement for height adjustment. Because both the column height and boom height are adjustable, some amount of coordination is useful to help make it more natural to switch between various height positions, preferably so that the technician can concentrate attention on obtaining the best setup conditions for exposure without excessive concern for setting or adjusting column height relative to boom height.
Thus, there is a need for improvements in mobile x-ray apparatus design that allow ease of height adjustment of a collapsible column relative to the height of its boom transport mechanism.